Both end-hydroxyl group-terminated diols are industrially useful as starting materials for resins such as polyester resins and polyurethane resins. Particularly, 1,3-propanediol is a compound having a great potential demand as a starting material for synthetic resins, particularly as a starting material for polyester fiber. Therefore, studies are being made to develop a process for producing this compound, at low cost, by a chemical production procedure, a biological production procedure, etc.
Heretofore, as the process for chemically producing the 1,3-propanediol, there are known various processes including: a production process for 1,3-propanediol wherein 3-hydroxypropionaldehyde (hereinafter simply referred to as “3-HPA”) is synthesized by a hydration reaction of acrolein and the resultant product is then subjected to a hydrogenation reaction (Unexamined Japanese patent publication (“KOKAI”; hereinafter simply referred to as “JP-A”) Hei. 10-212253); and a production process for 1,3-propanediol wherein 3-HPA is synthesized by a hydroformylation reaction of ethylene oxide and the resultant product is then subjected to a hydrogenation reaction (JP-A Hei. 11-515021); etc.
In any of these conventional processes, 1,3-propanediol is produced by finally hydrogenating 3-HPA, and therefore, these processes have a problem that unreacted 3-HPA is liable to remain in the resultant 1,3-propanediol product. In a case where polyester is synthesized by using 1,3-propanediol containing a carbonyl compound such as 3-HPA, it has been pointed out that such 1,3-propanediol is liable to cause odor or coloring in the polyester.
Accordingly, the 1,3-propanediol product should preferably contain no carbonyl compound such as 3-HPA, as completely as possible. However, it is difficult to remove these carbonyl compounds by a general purification method such as distillation, e.g., as disclosed in JP-A Hei. 6-40973 and JP-A Hei. 11-509828, etc.
Under these circumstances, in order to obtain 1,3-propanediol having a low content of carbonyl compounds such as 3-HPA, JP-A Hei. 6-40973 discloses a method of subjecting 3-HPA to a hydrogenation reaction through two stages, and JP-A Hei. 11-509828 discloses a method of removing carbonyl compounds which have been contained in 3-HPA by utilizing the reaction of the carbonyl compounds with an alkali. However, in any of these methods, it is difficult to obtain a 100% conversion for 3-HPA, and therefore it is necessary to remove the carbonyl compounds remaining in the resultant 3-HPA product. Such a removing operation increases the load on the production process for 1,3-propanediol, and this becomes a cause for increasing the production cost of 1,3-propanediol.
For solving the above-mentioned problems, there has been investigated a process for chemically producing 1,3-propanediol while no 3-HPA is used as the starting material. As one of these methods, there is a conceivable method wherein an epoxy alcohol compound (i.e., glycidol in this case) is subjected to hydrogenolysis.
As the reaction for obtaining a diol compound by the hydrogenolysis of an epoxy alcohol, for example, a hydrogenolysis reaction of glycidol by a Pd/C catalyst in methanol has been reported by Sajiki et al., in Journal of Chemical Society, Chemical Communications, pp. 1041-1042 (1999). However, according to this method, only 1,2-propanediol is produced and it is reported that the intended 1,3-propanediol cannot be obtained. In general, it is difficult to obtain such a hydroxyl group-terminated alcohol by the hydrogenolysis of a terminal epoxy group.
On the other hand, U.S. Pat. No. 3,975,449 discloses a process wherein a both end-hydroxyl group-terminated diol is produced by subjecting a hydroxyl, group-terminated epoxy alcohol having a di-substituted oxirane ring represented by the following formula (4) to hydrogenolysis in a solvent of water, alcohol or amide.
(wherein R3 represents an alkylene group having 1 to 5 carbon atoms, and R4 represents an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 1 to 5 carbon atoms).
However, even in the method disclosed in this Patent publication, the selectivity factor corresponding to the conversion of the hydroxyl group-terminated epoxy alcohols having a mono-substituted oxirane ring represented by general formula (1) into both end-hydroxyl group-terminated diols is low, and Practical Example 6 of this Patent publication discloses that the selectivity factor corresponding to the conversion from glycidol into 1,3-propanediol is extremely low.
General Formula (1):

On the other hand, German Patent No. 1,139,477 discloses a process wherein a hydroxyl group-terminated alcohol is produced with a relatively good selectivity by the hydrogenolysis of 1,2-epoxyalkane which is a hydroxyl group-terminated epoxide having a mono-substituted oxirane ring. This patent publication has achieved an improvement in the selectivity for hydroxyl group-terminated alcohols in the hydrogenolysis of hydroxyl group-terminated 1,2-epoxyalkane having a mono-substituted oxirane ring, while such an improvement had been difficult until that time.
However, even by this method disclosed in this patent publication, the selectivity is not sufficiently high, unless the substituent of the oxirane ring has 7 or more carbon atoms, and it is found to be difficult to obtain hydroxyl group-terminated alcohols, similarly to the conventional methods.
As described above, there has never been known a process wherein an intended both end-hydroxyl group-terminated diol (such as 1,3-propanediol) is efficiently produced by the hydrogenolysis reaction of an epoxy alcohol compound (such as glycidol) with the number of carbon atoms in the substituent thereof being as small as 6 or less, among hydroxyl group-terminated epoxy compounds having a mono-substituted oxirane ring.